In the sixties, chess was thought to be a problem that required intelligence since it couldn't be brute-forced. We now have machines which can play it well, without brute-forcing, and yet it's seen as entirely procedural.
As for style transfer, that is a very specific skill of making the patterns of one style map to the patterns of another. I am not particularly well versed with art, but that process seems well defined to me.
Perhaps your issue is with my more generalized definition of "clear" and "well-defined". I meant to use these terms to distinguish between autonomous driving and being a successful human. I really don't think there is anywhere close to a consensus on the latter. To the extent that there is, then yes, AI should be able to do it.
Of course we don't have human-level AI right now, but if that's the only thing you're claiming it's pretty vacuous.
Note that we have great raster-based deep visual effects, but vector is... not there yet (not saying it won't be) - vector is less structured than raster, so the choice of algorithm is less obvious.
As for well-defined criteria, I don't think that's really quite the right standard, I think the correct standard is that there is a way of metrizing success on a well-ordered set (like the [0,1] interval), even if it's noisy.